Usually, high resilience polyurethane foam is produced by reacting polyether polyol with an organic isocyanate and water, said polyether polyol having at least two hydroxyl groups per molecule and more than 20% of said hydroxyl groups being primary hydroxyl groups. High resilience polyurethane foam thus produced is called cold cure type polyurethane foam because it needs little or no oven curing which is essential for ordinary heat curing polyurethane foams. Such a foam finds a variety of uses as cushioning materials for automobiles and furniture by virtue of its outstanding resilience, high load bearing properties (SAC factor), and low combustibility.
In the production of heat curing polyurethane foams, the well-known polysiloxane-polyoxyalkylene copolymer has been used as a foam stabilizer. Such a foam stabilizer, however, when added to a foaming composition for high resilience polyurethane foam, causes the resulting foam to shrink, due to its excessive foam stabilizing effect, to such an extent that it is difficult or impossible to obtain open-cell structure by crushing cell membranes. If no foam stabilizer is used at all, the resulting slab stock foam becomes very coarse in cell structure, causing collapse of foam. The absence of foam stabilizer in molded foams also results in coarse cell structure and voids on the molding surface. Thus, it has been a problem in high resilience polyurethane foam to obtain a surfactant which has a proper degree of cell stabilizing ability.